Vertical domestic heating unit



Feb. 23, 1943. A. J. GRINDLE VERTICAL DOMESTIC HEATING UNIT Filed Sept. 22, 1938 3 Sheets-Sheet l j Ugh/27% M411 W oaT foQljw C4ure VERTICAL DOMESTIC HEATING uun' Filed Sept. 22, 1938 3 Sheets-Sheet 2 re /Cy A. J. GRINDLE VERTICAL DOMESTIC HEATING UNIT Feb. 23, 1943.

Filed Sept. 22, 1938 3 Sheets-Sheet 3 Patented Feb. 23, 1943 UNITED STATES PATENT OFFICE VERTICAL DOMESTIC HEATING UNIT Aubrey J. Grindle, Chicago, Ill.

Application September 22, 1938, Serial No. 231,237

12 Claims.

This invention relates to heating units and more particularly concerns a vertical domestic heating unit adapted for burning pulverized fuel.

So far as I am aware there has not heretofore been developed a really practical heating unit for domestic purposes in which powdered or pulverized fuel can be used to advantage. This type of fuel is particularly desirable because of its low cost, and though it has been used industrially for a long time, domestic coal burning boilers and furnaces have been restricted to the use of solid fuels.

A principal object of the present invention is to provide a novel heating unit in which powdered or pulverized fuel may be utilized efficiently and which is adapted for any preferred type of domestic heating system such as hot water, vapor, steam or hot air.

Another object of the invention is to provide a vertical heating unit having the characteristics thus generally stated which is of simple, compact construction, which has improved means for effecting thorough and complete down-draft combustion and up-draft heat transfer and which has a substantially improved efficiency rating over heating units utilizing solid fuels.

A further object of the invention is to provide an improved vertical down-draft burner chamber and a combined expansion chamber and ash pit construction wherein the ash pit serves as an active part of the expansion chamber and is so constructed and related thereto as to provide an emcient receptacle for fly ash and other deposited solids.

Still another object of the invention is to provide an improved flue gas circulation system for a heating unit of this general type wherein solids are separated from the gases before they pass up the flue and are then returned to the ash pit of the heating unit.

A still further object of the invention is to provide a novel vertical heat transfer structure including means for circulating the gases of combustion therethrough and also for keeping the heat transfer surfaces clean of residual deposits.

Yet another object of the invention is to provide a novel hot air circulating system for a heating unit of this type wherein the temperature of the air is uniformly increased in a step-bystep manner by bringing it successively into heatabstracting contact with the heated surfaces of the heating unit substantially in the order of their heat transfer potentiality from lowest to highest.

Additional objects of the invention are to provide improved means for preheating the air utilized for combustion purposes, the provision of improved, self-cleaning sight means for the combustion chamber, and the provision of improved instrument supporting means.

Other objects and advantages will become apparent in the following description and from the accompanying drawings in which:

Figure 1 is a longitudinal vertical sectional view through a boiler construction embodying the principles of the invention. v

Fig. 2 is a horizontal sectional plan view through the boiler taken substantially along line 2-2 of Fig. 1.

Fig. 3 is an enlarged vertical sectional view of the instrument panel of the boiler taken substantially in the plane of line 3-3 of Fig. 2.

Fig. 4 is an enlarged fragmental sectional view through the upper end of one of the heat transfer tubes and the associated circulating and cleaning device.

Fig. 5 is a fragmentary top plan view of the vertical combustion chamber of the heating unit.

Fig. 6 is a longitudinal vertical sectional view through a modified form of the invention adapted for domestic hot air systems.

Fig. 7 is a sectional plan view taken substantially along the line 1-1 of Fig. 6.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiments, but it is to be understood that I do not thereby intend to limit the invention to the specific forms disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Referring to Figs. 1 and 2 which show an exemplary form of boiler embodying the features of the invention and particularly adapted for domestic hot water or steam, or vapor heating systems, a generally upright, preferably insulated boiler casing in has its base supported upon an upstanding rim II which defines an ash pit I! of suitable depth in the floor of the furnace room. Enclosing the boiler casing 10 in suitable spaced relation is a casing or cabinet I3 which serves to conceal the boiler and various of its appurtenances and which may be shaped and finished decoratively to impart an attractive appearance to the installation.

According to the present invention the boiler is constructed generally vertically for downdraft combustion and up-draft heat transfer.

To this end there is/provided within the boiler casing in a combustion chamber including a refractory-lined vertical, generally frusto-conical or bell shaped burner chamber H, the upper end of which opens through the boiler casing and is ber ll at approximately the water level of theboiler which is indicated by the line i 9.

By reason of the uniformly tapered or bell shaped character of the burner chamber l4, ignition of the fuel will be facilitated in the upper restricted portion thereof because of the heat radiating adjacency of the'refractory lining to the fuel inlet. Then, in the development of combustion, expansion can progress uniformly and without back pressure all the way to the lower end of the burner chamber where it opens into a horizontal elongated expansion chamber 20. This is an important relationship because complete gasiflcation of all combustible constituents of the fuel is essential in order to procure utmost heating efilciency therefrom. Moreover, the uniform taper of the burner chamber avoids accumulation of condensates thereon .or plugging of the passageway as has been'experienced with cylindrical types of burner chambers. In addition the ample, gradually increasing expansion room afforded the products of combustion avoids surging or back pressure or roar when the burning mass reaches the expansion chamber 20.

It has been found in practice that the unit operv ates practically noiselessly.

Within the combustion chamber 20 the gases of combustion attain full expansion, dropping a large portion of the non-combustible constituents or ash and passing horizontally into the rear portion of the expansion chamber which projects laterally beyond the burner chamber l4. There the expanded gases pass upwardly through a plurality of spaced parallel vertical heat transfer tubes II which open into the expansion chamber and extend in heat transfer relation through the boiler water. As the gases pass through the tubes 2| they are caused to circulate against or wipe the walls of the tubes by spiral plate members or circulators 22 which in the present instance are suspended within the tubes from vertical shafts 23.

It may be noted at this point that in addition to their function as gas circulators, the spiral members 22 serve also as tube cleaners. For this purpose the members 22 are adapted to be rotated within the tubes to scrape the sediment from the walls thereof and drop the sediment into the ash pit l2. One practical manner of accomplishing this is to have the suspension shafts 23 project upwardly through packing glands 24 in the top of the boiler casing in so that the outer ends of the shafts can be engaged by an appropriate tool and turned to impart the cleaning motion to the spiral members. Each of the shafts 23 may be held in place by'a thrust plate 25 connected thereto as by means of a cotter pin 21 and resting against a bearing ring 28 which encloses the associated packing gland 20. The packing glands prevent escape of the I0 past the shafts 28.

From the upper ends of the heat transfer tubes II, the spent gases of combustion pass horizontally through an exhaust chamber 2' and are delivered rearwardly into a generally vertical, hopper-like dust collector I. of substantially greater flow area than the exhaust chamber. Within the latter the combustion gases are permitted to expand so that entrained solids may drop out more freely and deposit in the bottom of the collector.

,In the present instance the dust collector is preferably formed with a diagonal lower wall 3i slanting toward the ash pit if. The solids which drop upon the slanting wall ll slide down toward a discharge duct 12 which is inclined in a plane substantially in continuation of the wall 31. The lower end of the discharge duct 32 communicates with a coaxial receiving duct 33 which opens through the boiler casing l0 into the rear wall of the expansion chamber 20 adjacent to the rim of the ash pit I! so that the discharged solids will pass into the ash pit in the region thereof least affected by the circulating products of combustion in the expansion chamber.

Passage of the products of combustion up the discharge passageway 32, 33 from the expansion chamber into the dust collector is avoided by a suitable trap which in the present instance comprises a one way flap valve 84. This valve will open automatically under the weight of a bulk of solids pushing thereagainst from above to permit the latter to discharge, but will automatically close of its own weight to prevent bypass of products of combustion from the expansion chamber 20. 4

From the dust collector 29 the expanded gases travel up a flue 35 which is prefer-ably directed at a slanting angle coextensive with the slanting wall 3! so that solids which may deposit from the gases in the flue can drop back into the dust collector freely.

It may be noted at this point that because of the generally vertical relationship of the several passages for the products of combustion and the constant communication of all passages with the ash pit i2 clogging of the unit will be avoided and cleaning except possibly at rare intervals dispensed with. Moreover, the fuel is so thoroughly consumed that what residue rem-sins in the ash pit if can easily be removed at intervals by suction means such as a vacuum cleaner.

A substantial supply of secondary air is supplied for supporting combustion in the burner chamber-Il, and before starting the burner 15, such air serves to clear the combustion and heat transfer passages of the system of possible accumulations of combustible gases. As shown, the secondary air enters the combustion chamber l4 above the burner I! through a suitable air duct 31 (Figs. 1 and 5), the latter extending upwardly from a blower 38 at the rear of the unit inside the casing II and then passing over the top of the boiler to the upper end of the chamber l4.

Preferably the secondary air ispreheated so as to facilitate proper combustion and for'this purpose a generally upright duct 39 is provided for drawing the heated air from within the top residual heat therefrom before entering the air tube 39. A suitable control over the secondary air supply to the burner may be effected by a valve 4|, herein of the sliding variety, interposed at a suitable point in the secondary air duct 31.

After the burner has been started, and from time to time during operation, it is often desirable to observe the characteristics of the flame in the burner chamber I4. For this purpose a sight tube 42 (Figs. 2 and 3) may be provided to pass through one side of the boiler into the chamber l4. Closing the outer end of the tube 42 is a sight glass 43. Products of combustion which might be forced into the sight tube 42 would have a tendency to becloud the sight glass 43, and provision is therefore made to prevent entry of such beclouding matter and thus avoid the necessity of cleaning the sight glass. According to the present invention air is continuously delivered to the sight tube 42 during operation of the burner so as to maintain the tube positively clear of the beclouding materials. To this end a bypass duct 44 is preferably connected into the secondary air duct 31 and communicates with the sight tube 42 adjacent to the sight glass 43. In order to assure continuous full pressure of the air in the sight tube, the by-pass duct is preferably tapped into the secondary air tube ahead of the control valve 4|. The relatively small volume of air which enters the burner chamber through the sight tubes 42 supplements the combustion air delivered by the duct 31.

In the preferred construction, the sight tube 42 preferably opens through an instrument panel 45 which may be mounted closely adjacent to the outer enclosure casing IS in spaced relation to the boiler casing I by means of studs 4'! extending from the latter for this purpose. Upon the instrument panel may be mounted any preferred gauges or other instruments used in connection with the boiler. Access to the instrument panel through the outer casing |3 may be had through a suitably hinged door 48.

In the modified form of heating unit shown in Figs. 6 and '7, which is particularly adapted for a domestic hot air heating system, the combustion and heat transfer characteristics are substantially the same as have already been described except that if desired, a modified form of dust collector 50 may be used. This modified dust collector may be in the form of a funnelbottom hopper which opens into the top of the expansion chamber 20. To prevent diversion of products of combustion from the expansion chamber into the collector 50 means such as a normally closed, counter-weighted, cone-shaped valve 8| may close the discharge opening thereof and open automatically under the weight of an accumulation of solids to drop the latter into the underlying ash pit |2 Means is provided in the hot air furnace for effecting circulation of the air to be heated in a novel manner to utilize the heat from the furnace most efficiently. To this end the air to be heated is drawn by a suitable fan blower 53 from a cold air duct 54 through proper filters 55 and is discharged to initially sweep the upper or burner end of the burner chamber M. This probably is the least heated part of the furnace, but will begin to elevate the temperature of the air. The air then travels horizontally above a horizontal baflie or partition 51 and between opposed vertical baiiles 58 into contact with the upper ends of the heat transfer tubes 2|. In this manner the cold air is gradually raised in temperature by first sweeping the cooler portion of the combustion chamber and then being directed to sweep the cooled but still substantially heated ends of the heat transfer tubes 2| before it is permitted to sweep the hotter parts of. the furnace.

At the rear of the furnace, the horizontal partition 51 has a substantial opening 5'! through which the now partially heated air passes downwardly to sweep past the dust collector I0 and then between the hottest portions of the heat transfer tubes 2|. Thereafter the air sweeps the lower and hottest end of the combustion chamber l4. While thus traveling the air also, of course, receives the heat transferred through the wall of the expansion chamber 20. The fully heated air then enters the mouth of a hot air duct 59 and is conveyed into any preferred heating system with which the furnace may be associated.

The travel of the air to be heated is indicated by appropriate arrows in Figs. 6 and "I.

From the foregoing it will be apparent that the invention provides an improved, efllcient domestic heating unit for consuming pulverized fuel. The fuel is completely consumed and the heat generated is utilized to the utmost. Even the heat within the outer cabinet is used for preheating the combustion air. The cleaning is no problem with this heating unit because solids drop which from the products of combustion will deposit into the common receptacle or ash pit from which they can be easily removed. Any preferred heating medium can be used efliciently with the present heating unit, and where such medium is air the special novel circulating system assures that the utmost in heating value will be derived from the pulverized fuel consumed.

I claim as my invention:

1. A heating unit construction particularly adapted for domestic use comprising, in combination, a heat-releasing structure including a down-draft combustion chamber, an up-draft heat transfer section for the products of combustion, and a passage leading therefrom near the top of the furnace unit for conducting the spent products of combustion to a flue; an enclosure for said structure having an air opening near the base thereof; a blower adjacent to the base of the enclosure and having a pressure duct communicating with the top of said down-draft combustion chamber to supply combustion air thereto; and a duct communicating with the upper interior portion of said enclosure to conduct to said blower air which has entered the enclosure through said opening and has been preheated by traveling in contact with said passage. 4

2. A domestic heating unit of the character described comprising, in combination, an upright down-draft combustion chamber, upright updraft heat transfer tubes communicating with said combustion chamber and located in spaced relation thereto, a casing enclosing said combustion chamber and said heat transfer tubes and providing an air circulation chamber, a horizontal partition within said chamber intermediate the upper and lower ends of said combustion chamber and said heat transfer tubes, means for forcing air to be heated successively against the upper end of said combustion chamber and then the upper ends of said heat transfer tubes, said partition having an opening for permitting the preheated air to pass downwardly through the partition after the air has passed in contact with the upper ends of said heat transfer tubes, and means below said partition providing a passage for the preheated air to travel successively in heat abstracting relation to the lower ends of said heat transfer tubes and the lower end of said combustion chamber, and means for conducting the heated air from said furnace casing.

3. A furnace construction of the character described comprising, in combination, a vertical combustion chamber, upright heat transfer means adjacent to said combustion chamber and communicating therewith to provide a passage from said combustion chamber for the hot products of combustion, a casing enclosing said combustion chamber and said heat transfer means and providing an air heating and circulation chamber, said chamber being divided into upper and lower sections and having an air passage through which the air to be heated must travel horizontally in one direction and then downwardly and horizontally in substantially the opposite direction, means for blowing air to be heated across the upper end of said combustion chamber, and means for thereafter directing the air to be heated against the upper portions of said heat transfer means before passing downwardly into the lower section of the circulating chamber.

4. A furnace of the character described adapted for a domestic heating system comprising, in combination, a vertical down-draft combustion chamber, vertical up-draft heat transfer tubes adjacent to said 'combustion chamber, means providing a continuous passage between said combustion chamber and said heat transfer tubes, means for creating a forced draft of air across the top of said combustion chamber and the upper ends of said tubes, means for diverting the air downwardly and successively across the lower ends of said heat transfer tubes and. the lower end of said combustion chamber, and means for conveying the heated air away from the furnace.

5. In combination with a heating unit construction of the character described including a combustion chamber and means providing a heat transfer passage for the products of combustion from said chamber, a dust collector communicating with said passage and providing an expansion and settling chamber to receive the spent products of combustion and separate solids therefrom, a flue for the separated gases leading at an upwardly slanting angle from one side of said dust collector so as to facilitate return to said dust collector of solids which may settle out of the spent gases in the flue, and means for controlled removal of the separated solids from the bottom of said dust collector.

6. In combination with a heating unit construction of the character described including a combustion chamber and means providing a heat transfer passage for the products of combustion from said chamber, a dust collector communicating with said passage and providing an expansion and settling chamber to receive the spent products of combustion and separate solids therefrom, a flue for the separated gases leadingat an upwardly slanting angle from one side of said dust collector so as to facilitate return to said dust collector of solids which may settle out of the spent gases in the flue, and a duct for removal of separated solids leading from the bottom of said dust collector in alinement with said'flue, the wall of said dust collector between the lower edge of said flue and the nearest edge of said duct lying in the same plane as the bottom walls of said flue and duct so as to form an unimpeded slideway to said duct for the solids separated out of the flue gases in said fiue.

7. In combination in a vertical domestic heating unit utilizing powdered fuel, a structure providing a substantially u-shaped path for the products of combustion wherein one leg of the,

U forms a vertical combustion chamber while the other leg forms a heat transfer passage and the web or base of the U forms an expansion chamber connecting the combustion chamber and the heat transfer passage, a downwardy directed powdered fuel burner mounted at the top of the combustion chamber including means for delivering fuel and air thereto, a. casing enclosing said U-shaped structure for confining a heating medium in heat absorbing relation to substantially all heated parts of said structure, and a cabinet wholly enclosing said casing in spaced relation and providing a heat insulating air space.

8. In combination in a'vertical domestic heating unit utilizing powdered fuel, means providing a substantially U-shaped path for the products of combustion wherein one leg of the U forms a vertical combustion chamber while the other leg forms a heat transfer passage and the web or base of the U forms an expansion chamber, a downwardly directed powdered fuel burner mounted at the top of the combustion chamber and having means for delivering fuel and air thereto, a casing enclosing said U-shaped means for confining a heating medium in heat absorbing relation to substantially all heated parts of said means, a cabinet wholly enclosing said casing in spaced relation and providing a heat insulating air space, and means also within the confines of said cabinet providing an enlarged dust separating chamber for receiving and conducting downwardly the separated products of combustion issuing from the top of said transfer passage.

9. In combination in a vertical domestic heating unit utilizing powdered fuel, means forming an elongated horizontal chamber of substantial size, a generally tubular vertical structure serving as a combustion chamber mounted upon and opening into the top of said horizontal chamber adjacent to one end of the latter, a powdered fuel burner mounted at the top of said structure for directing burning powdered fuel downwardly through said structure into said chamber, means laterally spaced from said vertical structure and mounted upon said horizontal chamber for conducting the products of combustion upwardly from the latter, means for drawing of! the spent products of combustion from the top of said last mentioned means, and an enclosure about said downwardly through said structure into said chamber, said structure having an upwardly tapering internal shape to accommodate fuel expansion and to facilitate dropping of fuel particles or ash down into said chamber, means laterally spaced from said structure and mounted upon said chamber for conducting the products of combustion upwardly from the chamber,

for receiving the spent products of combustion from said drawing-01f means including a flue for the separated gases and an outlet for separated solids communicating with said chamber at the end opposite said structure. I

11. In combination in a vertical domestic heating unit adapted for utilizing powdered fuel, a vertically arranged elongated down-draft combustion chamber having a burner structure at the top; means providing a vertical up-draft heat transfer passage in spaced relation to said combustion chamber; means forming an expansion chamber connecting the lower ends of said combustion chamber and said heat transfer passage; a vertically arranged dust collector in spaced relation to said heat transfer passage communicating with the upper end of said heat transfer passage; an enclosure about said combustion chamber, heat transfer means, dust collector and expansion chamber for confining air to be heated in heat transfer relation thereto; an air inlet near the top of said enclosure; an air outlet adjacent to the bottom of said enclosure; and means for directing the air entering through said inlet in a circuitous path first-into heat transfer relation to the upper end portions and thereafter into heat transfer relation to the lower end portions of said combustion chamber, heat transfer means and dust collector on the way to said outlet.

12. A heating unit of the character described having, in combination with an ash pit, a casing closing the ash pit and rising substantially above the same, an upright burner chamber in said casing opening toward the ash pit, an expansion chamber interposed between the burner chamber opening and the ash pit to accommodate the products of combustion discharged from the burner chamber, a plurality of tubular members extending upwardly from said expansion chamber generally parallel to the combustion 

